It goes without saying that the men who are vying for the Republican presidential nomination found serious flaws with the budget plan President Obama released Monday. But it got us thinking that this might also be a good time to dig into the budget plans offered by the GOP candidates.

"The main problem we have is the government is too big, and the debt is too big, and you have to cut spending — so you have to get people to come together," Paul said at a Fox News debate in December. "They have been coming together to increase spending for decades. We have to get them to come together to do the opposite."

Paul's goal is to eliminate the income tax altogether, which would mean drastic cuts to the government, both domestic and defense.

"We're going to cut programs," said Santorum at a CNN debate in late January. "We're going to spend — under my administration, we're going to spend less money every year — every year. Year to year to year the federal government amount of spending will go down for four years, until we get a balanced budget."

Former House Speaker Newt Gingrich says he, too, would balance the budget, by boosting the economy, modernizing and streamlining the government, and increasing domestic energy production.

At the late January CNN debate, he said: "My goal is to shrink the government to fit the revenue, not to raise the revenue to catch up with the government."

And he'd have to do some serious shrinking of the government to get the budget in balance, because according to one independent analysis, Gingrich's tax plan would bring in about $1.3 trillion less each year than under current law.

Santorum's tax plan would call for a similar annual reduction in federal revenue, and — in order to balance the budget — spending cuts to match.

"Which is very, very difficult to do over a short period of time," says Joshua Gordon, policy director for The Concord Coalition, a nonpartisan group devoted to fiscal responsibility.

Just to put the task Santorum and Gingrich would face into perspective, Gordon says, think about the congressional supercommittee, which last year failed to agree on $1.2 trillion in deficit reduction, which was to have been spread over a decade. "This would make you try and do that in just a single year, and then you would have to do it for every successive year as well," says Gordon. "And it really becomes an exercise in impossible math."

"And without raising taxes or sacrificing America's critical military superiority, I will finally balance the American budget," Romney said to applause last week at the Conservative Political Action Conference in Washington.

"The cuts in non-defensive programs would be huge," says Paul Van de Water, with the Center on Budget and Policy Priorities. "Over a half by 2021."

The center says that cuts in non-defense programs under Romney's plan would be 54 percent, to be precise, according to a recent analysis it conducted.

Veterans benefits, Medicare, food stamps, education funding — you name it — it would probably have to be cut, says Van de Water. "I don't see how non-defense cuts of this magnitude could possibly be achieved."

He's not just talking technically, but also in terms of political reality. Because any tax cuts or spending cuts would have to pass through Congress. And as much as members of Congress say they despise deficits, they are also loath to cut programs that keep voters back home happy.

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Transcript

MELISSA BLOCK, HOST:

This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.

ROBERT SIEGEL, HOST:

And I'm Robert Siegel. President Obama has unveiled his $3.8 trillion budget for the next fiscal year. We have details elsewhere in the program. Republicans were quick to criticize it. Senate Republican leader Mitch McConnell called it, quote, "not a budget but a campaign document." And for their part, the GOP presidential candidates are offering budget plans of their own. NPR's Tamara Keith has some details of what they're proposing.

TAMARA KEITH, BYLINE: All of the candidates want to cut government spending and balance the federal budget. They also want to cut taxes. Ron Paul says he'd shrink the federal government by $1 trillion in his first year as president. This was Paul at a Fox News debate in December.

(SOUNDBITE OF FOX NEWS BROADCAST)

REPRESENTATIVE RON PAUL: The main problem we have is the government is too big, and the debt is too big, and you have to cut spending. So you have to get people to come together. They have been coming together to increase the spending for decades. We have to get them to come together to do the opposite.

KEITH: Paul's goal is to eliminate the income tax altogether, which would mean drastic cuts to the government, both domestic and defense. Former Pennsylvania senator Rick Santorum says he'll commit to cut $5 trillion of federal spending in five years.

(SOUNDBITE OF CNN BROADCAST)

RICK SANTORUM: We're going to cut programs. We're going to spend - under my administration, we're going to spend less money every year - every year. Year to year to year, the federal government amount of spending will go down for four years, until we get a balanced budget. And you can't do that.

KEITH: This was from a CNN debate in late January. And we just faded down the part where he goes on to attack former House Speaker Newt Gingrich for proposing big ideas that cost too much money when you're trying to balance the budget. But Gingrich, too, says he'll balance the budget, by boosting the economy, modernizing and streamlining the government and increasing domestic energy production. Here he is at the same debate.

(SOUNDBITE OF CNN BROADCAST)

NEWT GINGRICH: My goal is to shrink the government to fit the revenue, not to raise the revenue to catch up with the government. And I think...

KEITH: And he'd have to do some serious shrinking of the government to get the budget in balance, because according to one independent analysis, his tax plan would bring in about $1.3 trillion less each year than under current law. Santorum's tax plan calls for a similar annual reduction in federal revenue and - in order to balance the budget - spending cuts to match.

JOSHUA GORDON: Which is very, very difficult to do over a short period of time.

KEITH: Joshua Gordon is policy director for The Concord Coalition, a nonpartisan group devoted to fiscal responsibility. Just to put the task Santorum and Gingrich would face into perspective, Gordon says think about the not-so-super supercommittee that failed to agree on $1.2 trillion in deficit reduction, and that was over a decade.

GORDON: And so this would make you try and do that in just a single year, and then you would have to do it for every successive year as well. And it really becomes an exercise in impossible math.

MITT ROMNEY: And without raising taxes or sacrificing America's critical military superiority, I will finally balance the American budget.

KEITH: In addition to protecting military spending from cuts, Romney has pledged to more or less leave Social Security alone for the next decade.

PAUL VAN DE WATER: The cuts in non-defense programs would be huge, over a half by 2021.

KEITH: Paul Van de Water is with the Center on Budget and Policy Priorities, and he's examined what Romney's campaign pledges would mean. Veterans benefits, Medicare, food stamps, education funding - you name it - it would probably have to be cut, says Van de Water.

VAN DE WATER: I don't see how non-defense cuts of this magnitude could possibly be achieved.

KEITH: Not just technically, but also in terms of political reality. Because any tax cuts or spending cuts would have to pass through Congress. And as much as members of Congress say they despise deficits, they are also loath to cut programs that keep voters back home happy. Tamara Keith, NPR News, the Capitol. Transcript provided by NPR, Copyright NPR.